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   1 /* net/sched/sch_teql.c "True" (or "trivial") link equalizer.
   2  *
   3  *              This program is free software; you can redistribute it and/or
   4  *              modify it under the terms of the GNU General Public License
   5  *              as published by the Free Software Foundation; either version
   6  *              2 of the License, or (at your option) any later version.
   7  *
   8  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/types.h>
  13 #include <linux/kernel.h>
  14 #include <linux/string.h>
  15 #include <linux/errno.h>
  16 #include <linux/if_arp.h>
  17 #include <linux/netdevice.h>
  18 #include <linux/init.h>
  19 #include <linux/skbuff.h>
  20 #include <linux/moduleparam.h>
  21 #include <net/dst.h>
  22 #include <net/neighbour.h>
  23 #include <net/pkt_sched.h>
  24
  25 /*
  26    How to setup it.
  27    ----------------
  28
  29    After loading this module you will find a new device teqlN
  30    and new qdisc with the same name. To join a slave to the equalizer
  31    you should just set this qdisc on a device f.e.
  32
  33    # tc qdisc add dev eth0 root teql0
  34    # tc qdisc add dev eth1 root teql0
  35
  36    That's all. Full PnP 8)
  37
  38    Applicability.
  39    --------------
  40
  41    1. Slave devices MUST be active devices, i.e., they must raise the tbusy
  42       signal and generate EOI events. If you want to equalize virtual devices
  43       like tunnels, use a normal eql device.
  44    2. This device puts no limitations on physical slave characteristics
  45       f.e. it will equalize 9600baud line and 100Mb ethernet perfectly :-)
  46       Certainly, large difference in link speeds will make the resulting
  47       eqalized link unusable, because of huge packet reordering.
  48       I estimate an upper useful difference as ~10 times.
  49    3. If the slave requires address resolution, only protocols using
  50       neighbour cache (IPv4/IPv6) will work over the equalized link.
  51       Other protocols are still allowed to use the slave device directly,
  52       which will not break load balancing, though native slave
  53       traffic will have the highest priority.  */
  54
  55 struct teql_master
  56 {
  57         struct Qdisc_ops qops;
  58         struct net_device *dev;
  59         struct Qdisc *slaves;
  60         struct list_head master_list;
  61 };
  62
  63 struct teql_sched_data
  64 {
  65         struct Qdisc *next;
  66         struct teql_master *m;
  67         struct neighbour *ncache;
  68         struct sk_buff_head q;
  69 };
  70
  71 #define NEXT_SLAVE(q) (((struct teql_sched_data*)qdisc_priv(q))->next)
  72
  73 #define FMASK (IFF_BROADCAST|IFF_POINTOPOINT)
  74
  75 /* "teql*" qdisc routines */
  76
  77 static int
  78 teql_enqueue(struct sk_buff *skb, struct Qdisc* sch)
  79 {
  80         struct net_device *dev = qdisc_dev(sch);
  81         struct teql_sched_data *q = qdisc_priv(sch);
  82
  83         if (q->q.qlen < dev->tx_queue_len) {
  84                 __skb_queue_tail(&q->q, skb);
  85                 sch->bstats.bytes += qdisc_pkt_len(skb);
  86                 sch->bstats.packets++;
  87                 return 0;
  88         }
  89
  90         kfree_skb(skb);
  91         sch->qstats.drops++;
  92         return NET_XMIT_DROP;
  93 }
  94
  95 static struct sk_buff *
  96 teql_dequeue(struct Qdisc* sch)
  97 {
  98         struct teql_sched_data *dat = qdisc_priv(sch);
  99         struct netdev_queue *dat_queue;
 100         struct sk_buff *skb;
 101
 102         skb = __skb_dequeue(&dat->q);
 103         dat_queue = netdev_get_tx_queue(dat->m->dev, 0);
 104         if (skb == NULL) {
 105                 struct net_device *m = qdisc_dev(dat_queue->qdisc);
 106                 if (m) {
 107                         dat->m->slaves = sch;
 108                         netif_wake_queue(m);
 109                 }
 110         }
 111         sch->q.qlen = dat->q.qlen + dat_queue->qdisc->q.qlen;
 112         return skb;
 113 }
 114
 115 static struct sk_buff *
 116 teql_peek(struct Qdisc* sch)
 117 {
 118         /* teql is meant to be used as root qdisc */
 119         return NULL;
 120 }
 121
 122 static __inline__ void
 123 teql_neigh_release(struct neighbour *n)
 124 {
 125         if (n)
 126                 neigh_release(n);
 127 }
 128
 129 static void
 130 teql_reset(struct Qdisc* sch)
 131 {
 132         struct teql_sched_data *dat = qdisc_priv(sch);
 133
 134         skb_queue_purge(&dat->q);
 135         sch->q.qlen = 0;
 136         teql_neigh_release(xchg(&dat->ncache, NULL));
 137 }
 138
 139 static void
 140 teql_destroy(struct Qdisc* sch)
 141 {
 142         struct Qdisc *q, *prev;
 143         struct teql_sched_data *dat = qdisc_priv(sch);
 144         struct teql_master *master = dat->m;
 145
 146         if ((prev = master->slaves) != NULL) {
 147                 do {
 148                         q = NEXT_SLAVE(prev);
 149                         if (q == sch) {
 150                                 NEXT_SLAVE(prev) = NEXT_SLAVE(q);
 151                                 if (q == master->slaves) {
 152                                         master->slaves = NEXT_SLAVE(q);
 153                                         if (q == master->slaves) {
 154                                                 struct netdev_queue *txq;
 155                                                 spinlock_t *root_lock;
 156
 157                                                 txq = netdev_get_tx_queue(master->dev, 0);
 158                                                 master->slaves = NULL;
 159
 160                                                 root_lock = qdisc_root_sleeping_lock(txq->qdisc);
 161                                                 spin_lock_bh(root_lock);
 162                                                 qdisc_reset(txq->qdisc);
 163                                                 spin_unlock_bh(root_lock);
 164                                         }
 165                                 }
 166                                 skb_queue_purge(&dat->q);
 167                                 teql_neigh_release(xchg(&dat->ncache, NULL));
 168                                 break;
 169                         }
 170
 171                 } while ((prev = q) != master->slaves);
 172         }
 173 }
 174
 175 static int teql_qdisc_init(struct Qdisc *sch, struct nlattr *opt)
 176 {
 177         struct net_device *dev = qdisc_dev(sch);
 178         struct teql_master *m = (struct teql_master*)sch->ops;
 179         struct teql_sched_data *q = qdisc_priv(sch);
 180
 181         if (dev->hard_header_len > m->dev->hard_header_len)
 182                 return -EINVAL;
 183
 184         if (m->dev == dev)
 185                 return -ELOOP;
 186
 187         q->m = m;
 188
 189         skb_queue_head_init(&q->q);
 190
 191         if (m->slaves) {
 192                 if (m->dev->flags & IFF_UP) {
 193                         if ((m->dev->flags&IFF_POINTOPOINT && !(dev->flags&IFF_POINTOPOINT))
 194                             || (m->dev->flags&IFF_BROADCAST && !(dev->flags&IFF_BROADCAST))
 195                             || (m->dev->flags&IFF_MULTICAST && !(dev->flags&IFF_MULTICAST))
 196                             || dev->mtu < m->dev->mtu)
 197                                 return -EINVAL;
 198                 } else {
 199                         if (!(dev->flags&IFF_POINTOPOINT))
 200                                 m->dev->flags &= ~IFF_POINTOPOINT;
 201                         if (!(dev->flags&IFF_BROADCAST))
 202                                 m->dev->flags &= ~IFF_BROADCAST;
 203                         if (!(dev->flags&IFF_MULTICAST))
 204                                 m->dev->flags &= ~IFF_MULTICAST;
 205                         if (dev->mtu < m->dev->mtu)
 206                                 m->dev->mtu = dev->mtu;
 207                 }
 208                 q->next = NEXT_SLAVE(m->slaves);
 209                 NEXT_SLAVE(m->slaves) = sch;
 210         } else {
 211                 q->next = sch;
 212                 m->slaves = sch;
 213                 m->dev->mtu = dev->mtu;
 214                 m->dev->flags = (m->dev->flags&~FMASK)|(dev->flags&FMASK);
 215         }
 216         return 0;
 217 }
 218
 219
 220 static int
 221 __teql_resolve(struct sk_buff *skb, struct sk_buff *skb_res, struct net_device *dev)
 222 {
 223         struct netdev_queue *dev_queue = netdev_get_tx_queue(dev, 0);
 224         struct teql_sched_data *q = qdisc_priv(dev_queue->qdisc);
 225         struct neighbour *mn = skb->dst->neighbour;
 226         struct neighbour *n = q->ncache;
 227
 228         if (mn->tbl == NULL)
 229                 return -EINVAL;
 230         if (n && n->tbl == mn->tbl &&
 231             memcmp(n->primary_key, mn->primary_key, mn->tbl->key_len) == 0) {
 232                 atomic_inc(&n->refcnt);
 233         } else {
 234                 n = __neigh_lookup_errno(mn->tbl, mn->primary_key, dev);
 235                 if (IS_ERR(n))
 236                         return PTR_ERR(n);
 237         }
 238         if (neigh_event_send(n, skb_res) == 0) {
 239                 int err;
 240
 241                 read_lock(&n->lock);
 242                 err = dev_hard_header(skb, dev, ntohs(skb->protocol),
 243                                       n->ha, NULL, skb->len);
 244                 read_unlock(&n->lock);
 245
 246                 if (err < 0) {
 247                         neigh_release(n);
 248                         return -EINVAL;
 249                 }
 250                 teql_neigh_release(xchg(&q->ncache, n));
 251                 return 0;
 252         }
 253         neigh_release(n);
 254         return (skb_res == NULL) ? -EAGAIN : 1;
 255 }
 256
 257 static inline int teql_resolve(struct sk_buff *skb,
 258                                struct sk_buff *skb_res, struct net_device *dev)
 259 {
 260         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 261         if (txq->qdisc == &noop_qdisc)
 262                 return -ENODEV;
 263
 264         if (dev->header_ops == NULL ||
 265             skb->dst == NULL ||
 266             skb->dst->neighbour == NULL)
 267                 return 0;
 268         return __teql_resolve(skb, skb_res, dev);
 269 }
 270
 271 static int teql_master_xmit(struct sk_buff *skb, struct net_device *dev)
 272 {
 273         struct teql_master *master = netdev_priv(dev);
 274         struct netdev_queue *txq = netdev_get_tx_queue(dev, 0);
 275         struct Qdisc *start, *q;
 276         int busy;
 277         int nores;
 278         int subq = skb_get_queue_mapping(skb);
 279         struct sk_buff *skb_res = NULL;
 280
 281         start = master->slaves;
 282
 283 restart:
 284         nores = 0;
 285         busy = 0;
 286
 287         if ((q = start) == NULL)
 288                 goto drop;
 289
 290         do {
 291                 struct net_device *slave = qdisc_dev(q);
 292                 struct netdev_queue *slave_txq = netdev_get_tx_queue(slave, 0);
 293                 const struct net_device_ops *slave_ops = slave->netdev_ops;
 294
 295                 if (slave_txq->qdisc_sleeping != q)
 296                         continue;
 297                 if (__netif_subqueue_stopped(slave, subq) ||
 298                     !netif_running(slave)) {
 299                         busy = 1;
 300                         continue;
 301                 }
 302
 303                 switch (teql_resolve(skb, skb_res, slave)) {
 304                 case 0:
 305                         if (__netif_tx_trylock(slave_txq)) {
 306                                 unsigned int length = qdisc_pkt_len(skb);
 307
 308                                 if (!netif_tx_queue_stopped(slave_txq) &&
 309                                     !netif_tx_queue_frozen(slave_txq) &&
 310                                     slave_ops->ndo_start_xmit(skb, slave) == 0) {
 311                                         __netif_tx_unlock(slave_txq);
 312                                         master->slaves = NEXT_SLAVE(q);
 313                                         netif_wake_queue(dev);
 314                                         txq->tx_packets++;
 315                                         txq->tx_bytes += length;
 316                                         return 0;
 317                                 }
 318                                 __netif_tx_unlock(slave_txq);
 319                         }
 320                         if (netif_queue_stopped(dev))
 321                                 busy = 1;
 322                         break;
 323                 case 1:
 324                         master->slaves = NEXT_SLAVE(q);
 325                         return 0;
 326                 default:
 327                         nores = 1;
 328                         break;
 329                 }
 330                 __skb_pull(skb, skb_network_offset(skb));
 331         } while ((q = NEXT_SLAVE(q)) != start);
 332
 333         if (nores && skb_res == NULL) {
 334                 skb_res = skb;
 335                 goto restart;
 336         }
 337
 338         if (busy) {
 339                 netif_stop_queue(dev);
 340                 return 1;
 341         }
 342         dev->stats.tx_errors++;
 343
 344 drop:
 345         txq->tx_dropped++;
 346         dev_kfree_skb(skb);
 347         return 0;
 348 }
 349
 350 static int teql_master_open(struct net_device *dev)
 351 {
 352         struct Qdisc * q;
 353         struct teql_master *m = netdev_priv(dev);
 354         int mtu = 0xFFFE;
 355         unsigned flags = IFF_NOARP|IFF_MULTICAST;
 356
 357         if (m->slaves == NULL)
 358                 return -EUNATCH;
 359
 360         flags = FMASK;
 361
 362         q = m->slaves;
 363         do {
 364                 struct net_device *slave = qdisc_dev(q);
 365
 366                 if (slave == NULL)
 367                         return -EUNATCH;
 368
 369                 if (slave->mtu < mtu)
 370                         mtu = slave->mtu;
 371                 if (slave->hard_header_len > LL_MAX_HEADER)
 372                         return -EINVAL;
 373
 374                 /* If all the slaves are BROADCAST, master is BROADCAST
 375                    If all the slaves are PtP, master is PtP
 376                    Otherwise, master is NBMA.
 377                  */
 378                 if (!(slave->flags&IFF_POINTOPOINT))
 379                         flags &= ~IFF_POINTOPOINT;
 380                 if (!(slave->flags&IFF_BROADCAST))
 381                         flags &= ~IFF_BROADCAST;
 382                 if (!(slave->flags&IFF_MULTICAST))
 383                         flags &= ~IFF_MULTICAST;
 384         } while ((q = NEXT_SLAVE(q)) != m->slaves);
 385
 386         m->dev->mtu = mtu;
 387         m->dev->flags = (m->dev->flags&~FMASK) | flags;
 388         netif_start_queue(m->dev);
 389         return 0;
 390 }
 391
 392 static int teql_master_close(struct net_device *dev)
 393 {
 394         netif_stop_queue(dev);
 395         return 0;
 396 }
 397
 398 static int teql_master_mtu(struct net_device *dev, int new_mtu)
 399 {
 400         struct teql_master *m = netdev_priv(dev);
 401         struct Qdisc *q;
 402
 403         if (new_mtu < 68)
 404                 return -EINVAL;
 405
 406         q = m->slaves;
 407         if (q) {
 408                 do {
 409                         if (new_mtu > qdisc_dev(q)->mtu)
 410                                 return -EINVAL;
 411                 } while ((q=NEXT_SLAVE(q)) != m->slaves);
 412         }
 413
 414         dev->mtu = new_mtu;
 415         return 0;
 416 }
 417
 418 static const struct net_device_ops teql_netdev_ops = {
 419         .ndo_open       = teql_master_open,
 420         .ndo_stop       = teql_master_close,
 421         .ndo_start_xmit = teql_master_xmit,
 422         .ndo_change_mtu = teql_master_mtu,
 423 };
 424
 425 static __init void teql_master_setup(struct net_device *dev)
 426 {
 427         struct teql_master *master = netdev_priv(dev);
 428         struct Qdisc_ops *ops = &master->qops;
 429
 430         master->dev     = dev;
 431         ops->priv_size  = sizeof(struct teql_sched_data);
 432
 433         ops->enqueue    =       teql_enqueue;
 434         ops->dequeue    =       teql_dequeue;
 435         ops->peek       =       teql_peek;
 436         ops->init       =       teql_qdisc_init;
 437         ops->reset      =       teql_reset;
 438         ops->destroy    =       teql_destroy;
 439         ops->owner      =       THIS_MODULE;
 440
 441         dev->netdev_ops =       &teql_netdev_ops;
 442         dev->type               = ARPHRD_VOID;
 443         dev->mtu                = 1500;
 444         dev->tx_queue_len       = 100;
 445         dev->flags              = IFF_NOARP;
 446         dev->hard_header_len    = LL_MAX_HEADER;
 447 }
 448
 449 static LIST_HEAD(master_dev_list);
 450 static int max_equalizers = 1;
 451 module_param(max_equalizers, int, 0);
 452 MODULE_PARM_DESC(max_equalizers, "Max number of link equalizers");
 453
 454 static int __init teql_init(void)
 455 {
 456         int i;
 457         int err = -ENODEV;
 458
 459         for (i = 0; i < max_equalizers; i++) {
 460                 struct net_device *dev;
 461                 struct teql_master *master;
 462
 463                 dev = alloc_netdev(sizeof(struct teql_master),
 464                                   "teql%d", teql_master_setup);
 465                 if (!dev) {
 466                         err = -ENOMEM;
 467                         break;
 468                 }
 469
 470                 if ((err = register_netdev(dev))) {
 471                         free_netdev(dev);
 472                         break;
 473                 }
 474
 475                 master = netdev_priv(dev);
 476
 477                 strlcpy(master->qops.id, dev->name, IFNAMSIZ);
 478                 err = register_qdisc(&master->qops);
 479
 480                 if (err) {
 481                         unregister_netdev(dev);
 482                         free_netdev(dev);
 483                         break;
 484                 }
 485
 486                 list_add_tail(&master->master_list, &master_dev_list);
 487         }
 488         return i ? 0 : err;
 489 }
 490
 491 static void __exit teql_exit(void)
 492 {
 493         struct teql_master *master, *nxt;
 494
 495         list_for_each_entry_safe(master, nxt, &master_dev_list, master_list) {
 496
 497                 list_del(&master->master_list);
 498
 499                 unregister_qdisc(&master->qops);
 500                 unregister_netdev(master->dev);
 501                 free_netdev(master->dev);
 502         }
 503 }
 504
 505 module_init(teql_init);
 506 module_exit(teql_exit);
 507
 508 MODULE_LICENSE("GPL");